Despite widely publicized service outages and the presence of tube-based electronics at many locations, U.S. and international aviation authorities, as well as airlines and the military, are moving forward with their plan to take air traffic control technology into the 21st century
By J. R. Wilson
Air traffic controllers are finally taking part in a plan to ensure that new systems designs fit their needs. With that, the most massive upgrade of the U.S. air traffic control (ATC) system in history is moving back on schedule. The upgrade project comprises a wide range of separate programs, and is designed to lift the Federal Aviation Administration (FAA) and U.S. Defense Department from the vacuum tube era to the digitized 21st Century — often in a single leap.
A plethora of acronyms and code names revolves around the multi-billion dollar, decade-long ATC upgrade effort. Those familiar with the project deal day in and day out with often-confusing terms that describe pieces of the project, such as CNS/ATM, STARS, DASR, DSR, ADS-B, WAAS, LAAS, ATNAVICS, Micro-EARTS, RPS, Host, Capstone, SafeFlight 21, and Free Flight.
While all these sub-projects incorporate open-systems hardware and software, only a few are actually interlinked operationally. The road to upgrade the systems that control safe passage through the national air system (NAS) has rarely been smooth.
Several upgrade programs ran afoul of members of the air controllers` union, the National Air Traffic Controllers Association (NATCA), well into development when the controllers finally got a look at the new designs and found several "human factors" problems. These ranged from keyboard designs and readability issues on some new displays, to how work was divided among groups of controllers and an early attempt to eliminate the paper flight strips controllers use to keep track of information.
The programs that raised these human factors issues were delayed until technicians offered solutions that satisfied the controllers. Since then, NATCA has been closely involved in all aspects of design and implementation.
"No one has raised any new issues that would hold up any deployments, although they have kept the working group together to look at any future enhancements," says Dan Watts, the FAA`s product team lead for Display System Replacement. "Our strategy is to evolve this over time, which is why we have the NATCA team together to help define the evolution of the system/team interface. Much of this involves small human-factors elements, not syntax."
Display System Replacement is one of the two largest programs in the FAA upgrade plan, along with Standard Terminal Automation Replacement System (STARS), each budgeted at about $1 billion.
The Raytheon Command, Control, Communications, and Information Segment in Marlboro, Mass., was named prime on STARS in 1996. Raytheon is commissioned to upgrade civil and military terminal automation systems nationwide by replacing important ATC software and computers with a new commercial-off-the-shelf (COTS) system.
Raytheon engineers are designing STARS equipment to control aircraft operating in the congested airspace that surrounds large airports.
STARS was one of the systems that human factors problems hit hardest. Experts say the cause of its problems was the late addition of the controllers to the design and development effort. FAA Officials say the original program was primarily based on an existing product. Yet once the controllers came on board it quickly became clear they had their own ideas about how the system should be designed.
"Early on, there was an incorrect understanding that the controllers had bought into this type of procurement, but there just wasn`t enough involvement, as it developed," explains Peter Dunham, Raytheon`s deputy manager for domestic ATC. "For the past few months, the working relationship between the controllers, their union, the FAA, and Raytheon has become very close without any problems in understanding or doing the work, which is an improvement over the previous state. The program has been adjusted to go into operation in a more conservative manner, with several smaller sites before the bigger sites such as Washington."
The system that Raytheon experts designed for military air bases is moving to operational status with fewer delays. There are two primary reasons for this. First, military controllers do not deal with anywhere near the volume of air traffic facing their civilian counterparts. Second, their training is somewhat different. They prefer a QWERTY keyboard, while civilian controllers insist on an ABC keyboard, for example.
The military version of STARS is up and running at Eglin Air Force Base, Fla., where engineers are making final software adjustments. The final operational test and evaluation phase is scheduled to conclude by the end of the year.
In many ways, officials say, the military ATC system had become even more outmoded than the civil version; even a simple STARS system installation is considered a major improvement. During the next two years, however, there will be a convergence of the military and civilian systems, which will be identical long before the FAA side is fully operational in 2007 (two years later than the original deadline due to the "human factors" delays).
While the operational target for Eglin is next April, program officials predict they will beat that date. The second military site will be McGuire Air Force Base, N.J., which is scheduled for initial operating capability (IOC) in December 2001.
The systems are a collection of Sun workstations, Sony cathode ray tube monitors (provided by the FAA, but a standard product), as well as some high-resolution monitors for towers and some specialized consoles. The primary activity is not hardware design and development, but software.
Basically, the same equipment will be at all sites, varying in quantity and configuration depending on the size of the center. Most of the software comes from Raytheon, and is an evolution of its standard AutoTrac system. This software, which is currently used in 10 other countries, adapts not only to the FAA`s NAS structure, but also to its and human-factors requirements. These requirements are somewhat different in the U.S. from how they are elsewhere in the world.
Departure from COTS
The human-factors issue had one other substantial influence on STARS, officials say. It is now essentially a development effort rather than a COTS initiative. "Because of the changes we`ve made to the system, we no longer advertise it as COTS," says Carol Bell, the FAA`s terminals financial and information officer. "We`re doing a human factors evaluation on the full service system this summer. The outcome of that will determine the schedule for the development required to get the system up to the point desired by the controllers and then getting it installed."
Those changes and the system delays also have added to the overall cost of STARS. Still, a strategic restructuring of the program in April made achieving full service the prime objective, and provided a new vision that may save time and money in the long run.
"Before this retrenching, the team did not have a clear path that would allow us to deliver a system out there," Bell says. "Now we have something all the partners agree on. "We were going to Eglin with one configuration, to Washington National with a different configuration, none of which was getting us where we wanted to be." Today, however, "we are firmly on the road to fielding a successful system."
Display System Replacement (DSR)
DSR is unique among the ATC upgrade programs because it is under budget, despite some delays and human factors problems. Originally budgeted at $1.055 billion, $24 million in underruns have been reported so far, with more expected as the program moves forward, says the FAA`s Watts.
DSR replaces 20-to-30-year-old equipment at the 20 FAA en-route centers with upgraded color displays, as well as new consoles, computer hardware, and software. It also provides a platform for future upgrades to increase productivity and system efficiency.
"We have completed operational readiness demonstration at five sites — Seattle, Salt Lake City, Cleveland, Dallas/Fort Worth, and Chicago," Watts says. "Those are all fully operational. In addition, we have [started initial operating capability] at New York, Houston, and Denver — all three of which should be fully operational by the end of September. The remaining 12 are scheduled to be fully operational by the end of May 2000, with the last two being Washington, D.C., and Indianapolis."
One part of the program that could help reduce bottlenecks and improve nationwide traffic flows is the User Request Evaluation Tool (URAT), part of the pre-flight program. Prototypes that controllers are evaluating in Indianapolis and Memphis enable controllers to project routes into the future. Using filed flight plans, controllers can make 20-minute projections of the airspace for which they are responsible. With this, the controller can tell quickly if he must vector an aircraft off its flight plan to avoid conflicts.
FAA officials have established a "core capability limited deployment" of URAT at seven sites — including Indianapolis and Memphis — that they believe have the greatest problem with bottlenecks. URAT, which will involve new hardware and software, will have the ability to take data from Host, run it through a new processor, and write directly to a monitor at the controller data position (one of three DSR positions, along with the radar and assistant consoles).
"URAT is a good example of where we have a system with all IBM processors running IAX (IBM`s version of Unix) and will be inserting new algorithms on a Sun processor running a different version of Unix. We`re finding out what it takes to make all those work together," Watts says.
"We`re using commercial operating systems and all of our network protocols are standards-based, but we also had a lot of unique requirements," he continues. The project is complex, to say the least. As computer hardware rapidly changes, he explains, designers must take care to match each new generation of hardware and software. Otherwise, "you eventually would get into situations where it would be hard to just replace a box because the [operating system] may not run on that platform, so you may need to upgrade the software as well."
But an open architecture also creates another problem that may seem the antithesis of its original intent — to avoid ever again having a system so far out of date tech-nologically that it must be replaced wholesale. That problem is not technology, but politics.
"If you try to stay current just for the sake of staying current, you will have technology challenges, but you also will have to justify budgets to replace equipment that is not necessarily no longer maintainable, but is simply obsolete," Watts explains. "That can tie our hands in terms of evolving the system. We`re good at justifying programs for equipment that have failing vacuum tubes and get big headlines, but when you`re just trying to stay current with technology and keep the system open and able to evolve, it`s a harder sell to make. But not doing it will create the same bow wave effect, where you will have to make a major system replacement in 10 years because you won`t be able to find replacement parts or software. We also have a lot of different commercial software components and we`ll have those same problems there."
Host and Oceanic Computer System Replacement (HOCSR)
HOCSR is replacing the main processors at 20 en-route air traffic control centers and three oceanic sites. The upgrade is to eliminate Y2K and supportability problems with the old Host system`s aging IBM 3083 computers on the en-route side and IBM 4381s on the oceanic side. Designers also are replacing a communications subsystem on the oceanic side for the same reasons with a Series/1 Replacement (S1R), which is the interface between the computers.
Engineers are replacing the 3083 and 4382 computers with the IBM Generation 3 (G3) System/390-based processors. The S1R is an IBM RISC 6000 system.
Experts from Lockheed Martin Air Traffic Management in Rockville, Md., are the HOCSR integrators, with IBM in Poughkeepsie, N.Y., providing the computer subsystem, and Sunhillo Corp. of Berlin, N.J., providing the communications subsystem SIR. FAA software experts are doing most of the software in-house at the FAA Tech-nical Center in Atlantic City, N.J.
All 23 sites are to be completed by the end of September, only 16 months after the first equipment was received at the Tech Center for testing.
"This is a four-phase program. The first phase was to get the new processors in place by September 1999," says Kathy Smith, FAA co-product team lead for HOCSR. "The second phase is to upgrade the software to use the G3 operating system. Phases 3 and 4 have to do with replacing peripherals that also have supportability issues, such as communication controllers, tape drives, high-speed printers, and so forth. We`re still in the planning phase on 3 and 4. Phase 2 is in the final stages of testing and we`ll be going out to key site testing later this year."
Realizing they could not complete a full-up system in such a short time, FAA leaders opted to address the most immediate problems of supportability and Y2K in Phase 1, adds team co-lead Faye Jordan.
"As we look at Phases 3 and 4, we are analyzing going to an open architecture," she says. "Right now, if a high-speed printer or some other peripheral goes down, it brings the NAS down. It`s the way applications and software run. An open architecture would help with that. That also was one reason for going with the new operating system — the G3 and its operating system set the stage for 21st century operations and state-of-the-art technology."
The intent is to provide increased functionality through an infrastructure that supports growth through single-card upgrades that eliminate the need to replace entire systems each time technology takes a step forward. With the G3 at its heart, the design is to allow technology upgrades and sustainment at least through 2008.
According to Jordan, that is just the beginning of the savings HOCSR should bring to the FAA: "This is state-of-the-art technology, so we have greater reliability and lower costs of ownership. We reduce our energy costs by about $15.6 million through 2008. We will be operating at 32 million instructions per second, up from 7 million instructions per second. And we saved a lot of space — going down from 900 square feet to 74 square feet per site. We`re increasing our operator efficiency and reducing heat generation."
The new system is much faster than the one it replaces, Jordan says. Operations that used to take up to two hours, for example, now can be done in a matter of minutes. "There also is redundancy throughout the system, so every component has a backup, from the main computers down to the power supplies. We also have reduced maintenance requirements by up to 65 percent."
Automatic Dependent Surveillance-Broadcast (ADS-B)
Executives of air cargo carriers love ADS-B; those of passenger airlines do not think they need it; military, business, and general aviation leaders have serious reservations; European experts may force it on the U.S. as the FAA forced the Traffic Alert and Collision Avoidance System (TCAS) on Europe; and FAA officials say they believe time will resolve all issues.
Not since the FAA required all commercial aircraft carrying more than 10 passengers to install TCAS a decade ago has a new technology created a controversy such as ADS-B has in the aviation community. The Cargo Airline Association (CAA) sees it as a preferable alternative to installing TCAS aboard their aircraft — and Europe may require it on all aircraft, including those now equipped with TCAS.
ADS-B technology enables aircraft identification, position, altitude, vector, velocity, and other information to broadcast automatically to other aircraft and ground facilities via data link. This is far more information than provided by TCAS, which is part of the problem for some potential users. The military and business aviation communities, for example, object to an automatic broadcast of so much information about their aircraft.
Even so, ADS-B has strong support throughout aviation, including RTCA, a private, not-for-profit corporation in Washington that develops consensus-based recommendations on communications, navigation, surveillance, and air traffic management system issues for the FAA.
ADS-B uses Global Positioning System (GPS) data, which is more accurate than radar. ADS-B reports that data as fast as once a second, where radar reports aircraft positions anywhere from four to 12 seconds for a long-range radar. ADS-B also provides air-based velocity information, so the aircraft actually reports its ground speed and heading.
The system uses broadcast datalinks that transmit position information without any kind of interrogation, unlike a secondary surveillance radar, which interrogates the aircraft and gets a reply. That same broadcast mechanism also can send messages to the aircraft or exchange data among aircraft.
While the current design does not guarantee receipt of messages, other datalinks already in use or planned for the future would be able to guarantee point-to-point messaging.
This ground-to-air capability means ground stations, which would see an air picture that combines radar with ADS-B, could use Traffic Information Services-Broadcast (TIS-B) to share that overall view with any aircraft equipped to receive it. Thus in an environment where some aircraft have ADS-B and others do not, the ground station receiving the radar information about the non-ADS-B aircraft could broadcast that to the ADS-B equipped aircraft.
At the heart of ADS-B is Lockheed Martin`s Microprocessor-based En-route Automated Radar Tracking System (Micro-EARTS), an operational system for radar surveillance deployed at four FAA and four U.S. Department of Defense sites. This system is heavily dedicated to the use of COTS elements. For the current tests, ADS-B was inserted into existing Micro-EARTS operational systems.
"These are open systems that are scalable to the environment they run in," says Brad Culbertson, senior systems architect for datalink applications at Lockheed Martin Air Traffic Management. "Micro-EARTS is a system that can be scaled down pretty far. We are taking what we have learned in the process of inserting ADS-B into Micro-EARTS and seeing what it would take to insert it into other legacy systems, en route, and terminal. So as the technology evolves, we can be in a position to upgrade the systems being used to process radar data in the field to include ADS-B as that becomes feasible."
Another application of these datalinks is flight information service, which provides an ability to get weather and other aeronautic information from the ground to the cockpit.
Dave Ford, the FAA`s integrated product team leader for advanced technologies, says RTCA officials provided his relatively new group with guidance on nine different technologies to enhance system safety and efficiency — at least seven of which would use ADS-B technology.
His group is working with the CAA, the avionics industry, the military, and others on demonstration tests of those capabilities, collecting data on performance, human factors issues, and communications links to enable them to work well together. Following this phase, the concept will go to others to implement.
"For us to ever get to where the NAS is going to depend solely or in large part on ADS-B requires the industry to be equipped," Ford says. "That`s years down the road because they won`t equip until it becomes financially beneficial for them. But there is such a benefit, either from safety or a dollar perspective, for them to equip on their own. I believe, over the next decade or so, a large majority of the flying industry will equip."
Richard Lay is the FAA Safe Flight 21 product lead. He says the approach being taken with ADS-B, which could see it going into cargo aircraft in the next few years, is an example of how to get emerging technology out quickly into local areas where designers can use it without waiting for the architecture.
"The benefit of that is you don`t have to make major commitments until you`re sure the technology is sound. You can get the data implemented locally, then gradually proceed to migrate it elsewhere," he says. "The next major business decision would be sometime in 2020, according to our architecture, to replace all the radars and ground infrastructure. But in places like Alaska, where there are large spaces with no radar coverage, this technology can be used now."
Alaska is one of the areas where officials are testing ADS-B. The state is a large area without adequate current radar coverage and a heavy concentration of cargo flights. ADS-B also is part of a test in the Ohio River Valley region from mid-1999 through 2002. This is part of Safe Flight 21, a three-year joint government/industry initiative designed to demonstrate and validate, in a real-world environment, the capabilities of advanced surveillance systems and air traffic procedures associated with free flight. Using ADS-B and TIS-B as enabling technologies, the program will demonstrate the nine free flight operational enhancements selected by RTCA:
- weather and other information in the cockpit;
- cost-effective CFIT (controlled flight into terrain) avoidance;
- improved terminal operations in low visibility;
- enhanced see and avoid;
- enhanced en-route air-to-air operations;
- improved surface navigation for the pilot;
- enhanced surface surveillance for the controller;
- ADS-B surveillance in non-radar airspace; and
- ADS-B separation standards.
The program also will demonstrate and quantify operational benefits, demonstrate capabilities, evolve procedures, and collect data on the performance of three candidate digital links: Mode Select (Mode S) Extended Squitter, Universal Access Transceiver (UAT), and VHF Data Link (VDL) Mode 4.
"The whole thrust of the ADS-B program in conjunction with Safe Flight 21 has been to identify immediate uses for ADS-B and then incrementally add functionality as the ATC system and the carriers that use it desire," notes CAA spokesman Ken Shapiro. "So there are other applications as well we will be working on, such as closely spaced parallel approaches to parallel runways that don`t have adequate separation for IFR parallel operations, such as San Francisco. When San Francisco goes to instrument flight rules, it really bogs that airport down. It might be possible to devise a paired approach program there, although that would take some ATC changes.
"ADS-B is a technology that is ready today and there`s no reason to wait for it," he continues. "Part of the reason for pushing the [operation/evaluation] was we want to get all the data to certify the system fleetwide and get it into our airplanes as quickly as possible for enhanced see-and-avoid and aid to visual acquisition applications. What we get out of that-and what we demonstrated at [operation/evaluation] — is that by providing pilots with that tool in the cockpit, we can have more efficient visual approaches at our hubs. We think you can improve the efficiency of the hub by about 20 percent under VFR conditions."
Areas such as Alaska and the Gulf of Mexico within the U.S. air system, as well as vast stretches of Canada, China, Russia, Africa, and Australia are obvious potential beneficiaries of ADS-B, which could detect potential conflicts as far away as 150 nautical miles.
Officials from RTCA, the FAA, and industry are working to create standards for which software can be written to use ADS-B for conflict detection. Officials are optimistic they can have simple conflict detection certified by sometime next year and have ADS-B resolution advisories operational by the fourth quarter of 2002.
ADS-B is already undergoing ATC experiments in Northern Europe, and E urocontrol has had observers at the U.S. demonstrations.
"The resolution part of ADS-B is intriguing because it takes you about half-way to Free Flight. The resolution can be projected to the pilots and the controller and allow them to negotiate a solution. Or, if it happens at closer range, both cockpits and the ground could, with the proper equipment, see the same information even if there was no time to discuss it," Shapiro says.
"The bottom line is that this technology is here today and, while the ultimate iteration of it may be Free Flight in 10 or 20 years."
This drawing represents the architecture of Oceanic Displays and Planning System portion of the Host and Oceanic Computer System Replacement, part of a major overhaul of the U.S. Air Traffic control system. this open-systems design makes broad use of commercial off-the-shelf equipment.
Pictured is the sensor vehicle of the Air Traffic Navigation, Integration and Coordination System (Atanvics) also known as the AN/TPN-31. The sensor vehicle consists of a primary surveillance radar, a secondary surveillance radar/Identification Friend or Foe, and a precision approach radar.